Cell Biology Basics

Cell Structure

• Plasma membrane: semi-permeable membrane that separates the cell from its environment
• Cytoplasm: jelly-like substance inside the cell membrane, where metabolic processes take place
• Nucleus: control center of the cell, contains genetic material (DNA)
• Mitochondria: energy-producing organelles, responsible for cellular respiration
• Endoplasmic reticulum: network of membranous tubules and cisternae, involved in protein synthesis and transport
• Ribosomes: small organelles, site of protein synthesis
• Lysosomes: membrane-bound sacs, contain digestive enzymes for breaking down and recycling cellular waste
• Golgi apparatus: complex of flattened sacs, involved in protein modification and secretion

Cell Functions

• Metabolism: conversion of energy and nutrients into usable forms
• Growth and development: increase in cell size and number, differentiation into specialized cells
• Response to stimuli: ability to react to changes in environment, e.g. light, temperature, touch
• Reproduction: creation of new cells through cell division (mitosis or meiosis)
• Cell signaling: communication between cells, through chemical signals (hormones, neurotransmitters)

Cell Types

• Prokaryotic cells: lack nucleus, typically small and simple, e.g. bacteria
• Eukaryotic cells: have nucleus, typically larger and more complex, e.g. plants, animals, fungi
• Stem cells: undifferentiated cells, capable of differentiating into various cell types

Cell Division

• Mitosis: division of somatic cells, results in two identical daughter cells
• Meiosis: division of reproductive cells, results in four non-identical daughter cells with half the number of chromosomes as the parent cell